In a variety of different power supply circuits, such as linear and switching power regulators, a pass-transistor, such as a pass-field-effect transistor (pass-FET), can be implemented to drive a capacitive load, such as a capacitor. In low voltage applications, such as to achieve low switch resistance and to avoid occupying a large amount of space in an integrated circuit (IC), the control voltage (e.g., gate voltage) of the pass-transistor can be incrementally increased, such as via a charge pump. The control voltage can be incrementally increased very quickly to increase an activation time of the switch and thus to increase a charging time of the capacitive load. However, such a rapid incremental increase in the control voltage can result in a large inrush current that can be harmful to both the pass-transistor and an associated voltage supply (e.g., battery).
One typical solution to limiting inrush current is to decrease the rate of incremental increase of the control voltage of the pass-transistor. However, by decreasing the rate of the incremental increase of the control voltage, an amount of time to charge a capacitive load is increased. Another typical solution to limiting inrush current is to switch to a different pass-transistor to reduce current-flow as the capacitive load is charged. However, to reduce the current-flow to limit inrush current, the current-flow to the capacitive load is decreased to such a degree as to also increase the charging time of the capacitor. Yet another typical solution to limiting inrush current is to pull-down on the control voltage upon detecting a large amount of inrush current. However, pulling-down on the control voltage depletes both the current-flow through the pass-transistor and the stored charge in the capacitive load. As a result, performance of a power supply circuit can be detrimentally affected by any of these typical solutions.